The motor mounts shown on the 3.5L were identical to my 6's 3.0L and its stated the packaging size of the 3.5L is the same as the 3.0L.
The engine is all new from the block up, though many Ford parts bin parts like the intake variable cam timing system. The block recieved a new casting process which has left it open deck, but they said with the new process, it's stronger than the former 3.0's closed deck (I still say fill it up and close off the block if you buy one).
